EAGER: Collaborative Research: A Novel Method for Laminar Burning Speed Measurement at Ultra High-Pressures

下一代先进燃烧装置将在超高压条件下运行，以提高燃烧效率，减少污染物排放。然而，在这样的极端条件下，火焰往往变得不稳定，基本性质的实验测量变得具有挑战性。该项目的主要目的是提供高压下点火过程的时间和空间分辨率的详细测量。此外，测量方法和开发的计算模型将通过支持设计和优化在极端条件下运行的先进燃烧设备的预测能力，对燃烧和等离子社区产生广泛而有价值的影响。该项目还将包括重要的教育活动，包括课堂和社区参与，将研究整合到相关课程，本科研究计划，以及针对K-12学生的外展计划。该项目的主要目标是开发一种新的方法，在超高压下使用球形膨胀的火焰来测量点火影响区域的LBS。这一区域的复杂之处在于，核的生长速度不仅取决于化学反应，还取决于其他条件，如能量释放，以及辐射和传导能量损失。由于电离气体(即等离子体)的产生，这些术语都没有得到充分的评估。这项研究将通过实验和模型相结合的研究来填补这一广泛的知识空白，这些研究集中在三个具体目标上：(1)使用定义良好和控制良好的高压实验配置；(2)建立一个自洽的理论框架来解释能量放电对等离子体形成和初始火焰传播的影响；以及(3)修改现有的高保真直接数值模拟(DNS)程序，以解释等离子体核和点火过程的演化。在实验方面，该项目将结合先进的激光诊断技术，利用等离子体核传播的高速成像。等离子体性质将使用统计热力学进行计算。该项目首次旨在以高时间和空间分辨率从根本上了解控制超高压点火的基本物理化学过程。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The next generation of advanced combustion devices will operate under ultra-high pressure conditions in order to improve the combustion efficiency and reduce emission of pollutants. However, at such extreme conditions, flame tends to become unstable and experimental measurement of fundamental properties becomes challenging. The principal aim of this project is to provide a detailed time- and space-resolved measurements of the ignition process at high pressures. In addition, the measurement methodologies and developed computational models will have a broad and valuable impact on combustion and plasma communities by enabling predictive capabilities for designing and optimizing advanced combustion devices operating under extreme conditions. The project will also encompass significant educational activities, including classroom and community engagement, integration of research into relevant courses, undergraduate research program, and an outreach program for K-12 students.The main goal of this project is to develop a novel method to measure LBS in the ignition affected region using a spherically expanding flame under ultra-high pressures. The complication with this region is that, the kernel growth rate does not only depend on the chemical reaction but also on other terms such as energy discharge, as well as radiative and conductive energy losses. None of these terms has been adequately assessed, due to the generation of ionized gas (i.e., plasma). The proposed research will fill this broad knowledge gap via combined experimental and modeling studies focused in three specific aims: (1) using a well-defined and well-controlled high-pressure experimental configuration; (2) developing a self-consistent theoretical framework to explain the influence of energy discharge on the plasma formation and initial flame propagation; and (3) modifying an available high-fidelity direct numerical simulation (DNS) code to account for the evolution of the plasma kernel and the ignition process. On the experimental side, the project will utilize high-speed imaging of the plasma kernel propagation in conjunction with advanced laser diagnostics. The plasma properties will be calculated using statistical thermodynamics. This project, for the first time, aims to fundamentally understand the underlying physicochemical processes controlling the ultra-high pressure ignition in a high temporal and spatial resolution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.